Hydraulic drive for winding machine



p 25, 1956 E. DAVIS ET AL HYDRAULIC DRIVE FOR WINDING MACHINE 3Sheets-Sheet 1 Filed Sept. l3. 1954 INVENTORS MAURICE E.GRANT RICHARD E.DAVIS ATTORNEY 3 Sheets-Sheet Sept. 25, 1956 E. DAVIS ET AL HYDRAULICDRIVE FOR WINDING MACHINE Filed Sept. 13. 195 1 l mm M Q mm M Q 3 s G. A3 K m E 2? mm w 3 mm w W m 3 5 mm mm ow e.N VI A 4 1 B J n mm I fi wn wlmn .mnm t2 8 x \\\b 4/ & m m Z on 9. 5 m7, 2. m mm 12?. mos: I .22 mmmp H MM. Q on 8 N 1 E RICHARD E. DAVIS MW ATTORNEY g 0 mp 2. E. l m m.llll 1 nh j Sept. 25, 1956 R. E. DAVIS ET AL 2,764,365

HYDRAULIC DRIVE FOR WINDING MACHINE led Sept. 13, 1954 3 Sheets-Sheet 3FIG. 4

INVENTORS MAURICE E. GRANT RICHARD E. DAVIS ATTORNEY United StatesPatent HYDRAULIC DRIVE FOR WINDING MACHINE Richard E. Davis, Summit,Wis., and Maurice E. Grant,

Rockford, 111., assignors to The Oilgear Company, Milwaukee, Wis., acorporation of Wisconsin Application September 13, 1954, Serial No.455,414

20 Claims. (Cl. 242-75) This invention relates to hydraulic drives forwinding machines and more particularly to a winder drive for the typeemployed to drive a winding shaft upon which a sheet, strip or strand offlexible material is wound into a roll as fast as the material isdelivered thereto from another machine or from another part of themachine of which the winding shaft forms a part.

A hydraulic winder drive includes a hydraulic motor which ismechanically connected to the winding shaft, a pump for supplying motiveliquid to the motor to enable it to drive the shaft, and means forincreasing the torque of the motor as the roll of material increases indiameter.

A winder drive must maintain tension on the material during the windingoperation and the tension must be maintained within close limits inorder to produce a roll of the desired density and to prevent thematerial from wrinkling, buckling or breaking or the inner turns of thematerial from moving axially during the winding of other turns outwardtherefrom.

The present invention has as an object to provide a winder drive capableof maintaining the correct tension upon flexible material while windingthe material into a roll.

Another object is to provide novel means for increasing the torque ofthe motor as the roll of material on the winding shaft increases indiameter.

Other objects and advantages will be apparent from the followingdescription of the winder drives shown schematically in the accompanyingdrawings in which the views are as follows:

Fig. 1 is a diagrammatic view illustrating the hydraulic circuit of apreferred embodiment of the invention and showing the relation of thevarious parts to each other, some of the parts being shown in full,certain parts being broken away to expose other parts and certain partsbeing shown in section.

Fig. 2 is a view similar to Fig. 1 but illustrating a dilferentembodiment of the invention. v

Fig. 3 is a view showing a'control valve which may be used in place ofthe control valves shown in Figs. 1 and 2.

Fig. 4 is a view similar to the right hand portion of Fig. 1 and showinga different means for compressing the spring of the control valve, themotor and the pumps being shown on a larger scale than in Fig. 1.

For the purpose of illustration the drive has been shown as beingemployed to drive the shaft 1 of a winding machine and cause it to winda strip of paper 2 thereon into a roll 3 as fast as the paper isdelivered by the delivery rolls 4 of a calender. Since the windingmachine, the calender and the paper do not per se form any part of thepresent invention, only parts thereof have been indicated in thedrawings.

Fig. 1

The drive shown in this figure includes a rotary hydraulic motor 5 whichis adapted to drive shaft 1 through a suitable drive 6 and a pump 7which delivers liquid to motor 5 through a channel 8 and has liquidreturned 2,764,365 Patented Sept. 25, 1956 to it through a channel 9 andwhich is driven in unison with rolls 4 such as by being driven by anelectric motor (not shown) having suitable controls.

Pump 7 may be of any type which has a member shiftable to vary itsdisplacement and a control which will cause the pump to discharge liquidat a predetermined maximum rate until pump pressure reaches apredetermined maximum and will then reduce pump displacement until thepump is delivering just enough liquid to maintain that pressureconstant.

For the purpose of illustration, the pump has been indicated as being ofthe rolling piston type disclosed in Patent No. 2,074,068 and as havinga pressure responsive control of the type disclosed in Patent No.2,080,810. Since both the pump and the control are well known and inextensive commercial use, it is deemed sufficient to state herein thatpump 7 has its mechanism arranged within a casing 10, that it has itspistons 11 arranged radially in a cylinder barrel 12 which rotates upona stationary axis, that the outer ends of pistons 11 engage an annularthrust member 13 which is arranged within a displacement varying memberor slide block 14 and is rotatably supported thereby, that slide block14 is shiftable transversely of the axis of cylinder barrel 12 but isrestrained by casing 10 from movement in any other direction, and thatpump 7 when driven will discharge liquid through channel 8 at a rateproportional to the distance that the axis of members 13 and 14 isoffset from the axis of cylinder barrel 12. Pump 7 is supplied withliquid from a reservoir 15 through a channel 16 which connects theintake side of pump 7 to reservoir 15 and has a check valve 17 arrangedtherein.

Slide block 14 is urged toward maximum displacement position by aconstant force, such as by a spring 20, and it is adapted to be movedtoward zero displacement position by hydraulic servo-motor shown ascomprising a cylinder 21, which is carried by casing 10, and a piston 22which is fitted in cylinder 21 and engages or is fixed to slide block14.

Liquid for operating servo-motor 21--22 is supplied thereto under thecontrol of a control valve 23 having its mechanismarranged within acasing 24 which in practice is attacheddirectly to pump casing 10 butwhich has been shown separate therefrom to simplify the drawing. Casing24 has formed therein an axial bore 25 which is connected at its lowerend to the discharge side of pump 7 by a pressure channel 26, an annulargroove or port 27 which is formed in the wall of bore 25 and isconnected to cylinder 21 by a channel 28 having a choke 29 arrangedtherein to limit the rate at which liquid can flow into cylinder 21, anda counterbore 30 which is larger than and concentric with bore 25 and isclosed at its upper end by a cover plate 31.

Flow of liquid into and out of cylinder 21 is controlled by a valvemember consisting of a valve element 34, which is closely fitted in bore25 and has at least one notch 35 formed in its lower end, and a piston36 which is fixed to element 34 and is closely fitted in counterbore 30.Any pressure created by pump 7 will extend through channel 26 into bore25 and tend to move valve member 34-36 upward against the resistance ofa spring 37 arranged between piston 36 and a piston 38 which is closelyfitted in counterbore 30 and provides between its upper face and thelower face of cover plate 31 a pressure chamber 39 to which liquid underpressure is supplied as will presently be explained.

The force exerted by spring 37 is initially regulated by an adjustingscrew 40 which is threaded through cover plate 31 and engages piston 38until the force exerted by the liquid in chamber39 exceeds the forcewith communicate when the valve is closed with an annular groove or port43 which is formed in the wall of counterbore and is connected tocylinder 21 by a channel 44.

The parts preferably are so constructed that the vertical distancebetween slots and 42 is exactly equal to the vertical distance betweenthe lower edge of port 27 and the upper edge of port 43. When thepressure created by pump 7 has reached a predetermined value asdetermined by the resistance of spring 37 or by the pressure in chamber39, it will have raised valve member 3436 until the bottom of slot 35 iseven with the lower edge of port 27 and the bottom of slots 42 are evenwith the upper edge of port 43 so that there is no flow of liquid eitherinto or out of cylinder 21.

Then a slight increase in pump pressure will cause valve member 3436 torise and permit liquid to flow from pipe 26 through bore 25, slot 35,port 27 and channel 28 into cylinder 21 and cause piston 22 to shiftslide block 14 toward the right to reduce pump displacement until pump 7is discharging just enough liquid to maintain pump pressure at apredetermined value. Conversely, a slight drop in pump pressure willpermit spring 37 or the pressure in chamber 39 to move valve member 3436downward to partly uncover port 43 so that liquid can escape fromcylinder 21 through channel 44, port 43 and counterbore 30 into drainchannel 41, thereby permitting spring 20 to move slide block 14 towardthe left to increase pump displacement until pump 7 is dischargingenough liquid to maintain pump pressure at the predetermined value.

Liquid is supplied to pressure chamber 39 by an auxiliary pump 45,indicated as being a gear pump, which has been shown separate from pump7 but in practice pump 45 is driven in unison with pump 7 and isarranged within the casing thereof as is customary. Pump 45 draws liquidfrom reservoir 15 and discharges it into a branched supply channel 46one branch of which is connected through a choke 47 to a channel 48having one end thereof connected to chamber 39 and the other end thereofconnected to the inlet of a resistance valve 49.

Choke 47 is provided in order that some of the liquid discharged by pump45 may be used for other purposes.

Liquid discharged into channel 48 will flow to exhaust throughresistance valve 49 which enables pump 45 to maintain in channel 48 andin chamber 39 a pressure proportional to the resistance of the spring 50of valve 49. The resistance of spring 50 is gradually increased inresponse to roll 3 gradually increasing in diameter as will presently beexplained.

In order to prevent damage to the parts in case pump pressure shouldrise so suddenly that the above described control could not reduce pumpdisplacement fast enough to prevent pump pressure from becomingdangerously high, the drive preferably is provided with an emergencysafety valve 54 having its mechanism arranged within a casing 55 whichin practice is a part of control valve casing 24 but which has beenshown separate therefrom in order to simplify the drawing.

As shown, casing 55 has formed therein an axial bore 56, a largerconcentric counterbore 57 arranged at the upper end of bore 56 andclosed at its upper end by a cover plate 58, a port 59 arranged at thelower end of bore 56 and provided in its lower wall with an annularvalve seat 60 through which when valve 54 is opened liquid may flow fromport 59 into an exhaust channel 61 which extends into reservoir 15.

Valve seat 60 is normally engaged by the lower end of a valve memberconsisting of a valve element 62, which is closely fitted in bore 56,and a piston 63 which is closely fitted in counterbore 57. Valve member62-63 is urged against valve seat 66 by a spring 64 arranged betweenpiston 63 and cover plate 58. Port 59 is con nected to the lower end ofbore 25 by a channel 65, that part of counterbore 57 below piston 63 isconnected to port 27 by a channel 66 having a choke 67 arranged therein,and that part of counterbore 57 above piston 63 is connected to exhaustby a drain channel 68.

The arrangement is such that, when the pressure created by pump 7becomes 'high enough to raise control valve element 34 until liquid canflow from channel 26 through bore 25, port 27 and channel 28 to cylinder21 and cause piston 22. to move slide block 14 toward the right tothereby effect a reduction on the displacement of pump 7 as explainedabove, pressure will extend through channel 66 into the lower end ofcounterbore 57 and, if the displacement of pump 7 is not reduced fastenough to prevent pump pressure from rising still higher, the pressurein the lower end of counterbore 57 will raise valve member 6263 andthereby permit enough liquid to flow from channel 26 through bore 25,channel and port 59 into exhaust channel 61 to prevent any furtherincrease in pump pressure.

In order to gradually-increase the pressure created by pump 7 as roll ofpaper 2 increases in diameter to thereby enable motor 5 to maintain aconstant or gradually varying tension on paper 2 as it is wound into aroll, the drive is provided with a hydraulic differential comprising asmall variable displacement hydraulic tachometer or pilot pump 7b, whichis driven at a speed proportional to the rotary speed of roll 3 such asby being driven from shaft 1 through a suitable drive 71, and a smalltachometer or pilot pump 72 which has a constant or preset displacementand is driven at a speed proportional to the linear speed of paper 2such as by being driven from roll 4 through a suitable drive 73.

Pilot pump has been indicated in the drawing as being of the samegeneral type as pump 7 so that detailed illustration and description isunnecessary. it is deemed. sufiicient to state that pump 74; has itsmechanism arranged within a casing 7 4, that it includes a displacementvarying memberor slide block 75 which is slidably fitted in casing 74and corresponds to the slide block 14 of pump 7, and that it includespistons, a cylinder barrel and a thrust member (not shown) whichcorrespond with pistons 11, cylinder barrel 12 and thrust member 13 ofpump 7 and are arranged within slide block 75. The control for pump 70differs from the control for pump 7 in that slide block 75 is urgedtoward a minimum displacement position by a spring 76 and is adapted tobe moved toward maximum displacement position by a servo-motorcomprising a cylinder 77, which is carried by casing 74, and a piston 78which is fitted in cylinder '77 and engages or is connected to slideblock '75.

Pump 78 has its outlet connected to the inlet of pump 72 by a channel'79 and its inlet connected to the outlet of pump '72 by a channel 30which is also connected to cylinder 77 by a branch 81 of channel 34Channels 75 and form with pumps "ill and 72 a closed hydraulic circuitso that all the liquid discharged by pump enters or attempts to enterpump 70. The pilot pump circuit is kept filled with liquid by connectinga branch of supply channel 46 to channel 79. In practice, two oppositelyopening relief valves are connected between channels 79 and 80 toprevent the pressure in the pilot circuit from exceeding a predeterminedvalue but since that is common practice the relief valves have beomitted from the drawings to allow more room for other parts.

The displacements of pumps 70 and 72 are initially so adjusted that,when paper 2 first starts to accumulate on shaft 1, the volume of liquiddischarged by pump 72 will be just sufficient to supercharge pump 70 ata low pressure. Then as the speed of shaft 1 decreases due to roll 3increasing in diameter as previously explained, pump 70 will be drivenat a progressively decreasing speed but pump 72 will continue tobedriven at a constant speed and will discharge liquid in excess of theliquid required to supercharge pump 70. The excess liquid will flowthrough branch channel 81 into cylinder 77 and cause piston 78 to moveslide block 75 toward the right to increase the displacement of pump 70in proportion to the decrease in its speed and thereby enable pump 78 toconsume all of the liquid delivered thereto by pump 72.

Movement of slide block 75 toward the right is proportional to theincrease in the diameter of roll 3 and that movement is utilized tocorrespondingly increase the pressure in chamber 39. As shown, a pushrod 82 is movable with slide block 75 and is pivotally connected to alever 83, which is pivoted at one of its ends upon a stationary support84, and lever 83 is pivotally connected to one end of an adjustingmember 85 which has its other end in engagement with resistance valvespring 50.

The arrangement is such that, when slide block 75 moves gradually towardthe right in response to an increase in the diameter of roll 3, push rod82 will swing lever 83 upon support 84 and lever 83 will cause member 85to gradually compress spring 50 to increase the resistance thereof andthereby enable auxiliary pump 45 to maintain a gradually increasingpressure in chamber 39. Push rod 82, lever 83 and adjusting member 35thus constitute thrust transmitting means for adjusting the resistanceof spring 50 in response to movement of slide block 75.

Means should be provided to adjust the initial compression of spring 58and to vary the ratio between further compression of spring 50 and themovement of slide block 75. The initial compression of spring 50 may beadjusted by providing between it and member 85 suitable shims which maybe varied as to number or thickness or by making member 85 extensiblesuch as by making it in two sections and connecting the two sections bymeans of a turnbuckle. The ratio between the movement of slide block 75and the resultant compression of spring 50 may be made variable such asby pivotally connecting member 85 to a block which is slidable in a slotformed in lever 83 and moving the block along the slot by means of ascrew. Since such means are old and well known, they have not beenillustrated and adjustment of spring 58 has been indicated by showingmember 85 connected to lever 83 by means of a pin 86 which may beinserted in any one of a plurality of holes 87 formed in lever 83.

OPERATION Assuming that the end of strip of paper 2 has been fastened toa suitable core fixed on winding shaft 1, that pilot pumps 76 and 72have been so adjusted that pump '72 will discharge liquid at a rate justsuflicient to supercharge pump 70 when the drive is started, and thatthe control for pump 7 has been so adjusted that pump 7 will create justenough pressure to enable motor 5 to exert just enough torque to exertthe proper tension on paper 2 when the drive is started, the drive willoperate as follows:

All slack in the paper between shaft 1 and roll 4 is taken up eithermanually or by inching the motor which drives pump 7. Then pump 7 may bestarted but, until rolls 4 are started, it cannot deliver liquid tomotor 5 which will cause pump pressure to rise and enable the pumpcontrol to reduce the displacement of pump 7 in the previously describedmanner until pump 7 is discharging just enough liquid to maintain apressure which will enable motor 5 to exert the correct tension uponpaper 2.

I Then when rolls 4 start to deliver paper to shaft 1, pumppressure willdrop slightly momentarily and permit the pump control to increase thedisplacement of pump 7 in the previously described manner until pump 7is discharging liquid at a rate and at a pressure which will enablemotor 5 to wind paper 2 into a roll 3 as fast as it is delivered theretoby rolls 4 and to maintain the desired tension on paper 2.

.As roll 3 increasesin diameter, the rotary speed ot shaft 1 willgradually decrease and decelerate motor 5 which will require less liquidthan is being currently discharged by pump 7 and the liquid dischargedby pump 7 in excess of the liquid required by motor 5 will flow throughcontrol valve 23 to cylinder 21 and cause piston 22 to graduallydecrease the displacement of pump 7 until it is discharging just enoughliquid to drive motor 5.

The gradual increase in the diameter of roll 3 requires that motor 5exert a gradually increasing torque in order to maintain the desiredtension upon paper 2. However, the'speed of pilot pump 70 will decreaseat a rate proportional to the rate at which the speed of shaft 1decreases so that all of the liquid currently discharged by pilot-pump72 cannot enter pump 70 and the excess liquid discharged by pump 72 Willenter cylinder 77 and cause piston 78 to move slide block graduallytoward the right to increase the displacement of pump 70.

Movement of slide block 75 toward the right effects a gradual increasein the resistance of valve 49 which enables auxiliary pump 45 togradually increase the pressure in chamber 39 of control valve 23 sothat pump 7 has-to create a gradually increasing pressure which enablesmotor 5 to maintain the desired tension upon paper 2 as roll 3 increasesin diameter.

If the tension on paper 2 should be maintained constant regardless ofthe diameter of roll 3, adjusting member is connectedto lever 83 in sucha position that resistance valve spring 51) is compressed at a rateproportional to the rate at which roll 3 increases in diameter. If it isdesired to increase or decrease the tension on paper 2 as roll 3increases in diameter, the connection between member 85 and lever 83 maybe moved along lever 83 in one direction or the other to increase ordecrease the rate at which spring 50 is compressed.

Fig. 2

The drive shown in this figure differs from the drive shown in Fig. 1 inthat the rate of delivery of motive liquid to the driving motor iscarried by bypassing a part of the liquid discharged by the main pumpinstead of by decreasing the displacement of the main pump.

Since the two drives are otherwise the same, only a brief description ofthe drive shown in Fig. 2 is deemed necessary because like parts havebeen indicated by like reference numerals and corresponding parts havebeen indicated by corresponding reference numerals with the exponent aadded to the reference numerals applied to Fig.2.

As shown, the winding shaft 1 is driven by a motor 5 through a drive 6and winds paper 2 into a roll 3 as fast as it is delivered by rolls 4.Liquid for energizing motor 5 is supplied thereto by a constantdisplacement pump 7 which has its outlet connected to the inlet of motor5 by a channel 8 and its inlet connected to the outlet of motor 5 by achannel 9.

The outlet of pump 7 is also connected by a channel 26 to the inlet of acontrol valve 23* which is the same as valve 23 except that port 43 andthe connections for channels 44, 65 and 66 are omittedand port 27 isconnected to a channel 28 which discharges into reservoir 15. Controlvalve 23 operates in the same manner as control valve 23 and thepressure in its chamber 39 is regulated in the same way and by the samemeans as in the drive shown in Fig. 1.

Pump 7 has suflicient volumetric capacity to enable it to dischargeliquid at a rate slightly in excess of the rate required by motor toenable it to drive shaft 1 at the correct speed when paper 2 firststarts to accumulate upon shaft 1.

The arrangement is such that, when paper 2 has been fastened to shaft 1and rolls 4 and pump 7* are started, the liquid discharged by pump 7 inexcess of the liquid required by motor 5 will flow through channel 26,move element 34 of valve 23 until the bottom of notch 35 is slightlywithin port 27 as shown, and then the excess liquid will flow throughvalve 23 and channel 28 into reservoir and the resistance of valve 23 tothe flow of liquid therethrough will cause pump 7 a to create justenough pressure to enable motor 5 to drive shaft 1 and to apply thecorrect tension to paper 2.

As paper 2 accumulates on shaft 1, the rotary speeds of shaft 1 andmotor 5 will gradually decrease due to roll 3 increasing in diameter. Asmotor 5 gradually decelerates, less liquid is required to drive it whichwill cause the flow of liquid through valve 23 to gradually increase.

The decrease in the speeds of shaft 1 and motor 5 will also cause thepressure in chamber 39 to gradually increase in the same manner as inthe drive shown in Fig. l and thereby cause the pressure created by pump7 to gradually increase and enable motor 5 to exert a graduallyincreasing torque as roll 3 increases in diameter.

Fig. 3

Since the control valve 23 shown in this figure is nearly the same asthe control valve 23 shown in Fig. 1, like parts have been indicated bylike reference numerals and corresponding parts have been indicated bycorresponding reference numerals with the exponent b" added to thenumerals applied to Fig. 3 so that only a brief description of valve 23is necessary.

Valve 23 differs primarily from valve 23 in that screw 40 is omittedtherefrom, piston 38 is replaced by an imperforate piston 38 and spring37 is replaced by a rod 37 The two valves function in the same mannerbut the closing force exerted upon valve member 34-36 of valve 23 may bedetermined by the adjustment of spring 37 until paper accumulates uponshaft 1 and then be determined by the pressure in chamber 39 while invalve 23 the closing force is determined at all times by the pressure inchamber 39.

However, if a choke 47 is inserted between chamber 39 and the auxiliarypump as shown in Figs. 1 and 2, a control valve having a spring ispreferred because the spring enables the valve to open or closeinstantly While without the spring movement of valve member 34--36causes liquid to flow through choke 47 which slows down the action ofvalve member 3436.

Fig. 4

The drive shown in this figure is substantially the same as the driveshown in Fig. 1 except that the resistance of the control valve springis varied mechanically instead of hydraulically. Therefore, only aportion of the drive has been shown in order to show certain parts on alarger scale and of the parts shown like parts have been indicated bylike reference numerals and corresponding parts have been indicated bycorresponding reference numerals with the exponent c added to thereference numerals applied to Fig. 4 so that a detailed description ofthe drive is unnecessary.

The drive includes a motor 5 which drives winding shaft 1 through asuitable drive 6, a pump 7 which is connected to motor 5 by channels 8and 9, a pilot pump 70 which is driven from shaft 1 through a suitabledrive 71 and is connected by channels 79 and 80 to the pilot pump 72(not shown) which is driven from delivery rolls 4.

The displacement of pump 7 is controlled by a control valve 23 which isconnected to the servo-motor cylinder 21 of pump 7 and to a safety valve54 in the same manner and by the same means as in the drive shown inFig. 1. Valve 23 differs from valve 23 in that cover plate 31 and piston38 are replaced by a piston 38 which is slidable in the upper part ofcounterbore 3t) and adapted to be moved mechanically in response tomovement of the slideblock 75 of pilot pump '70. Since valve 23 isotherwise the same as valve 23, like parts have been indicated by likereference numerals so that further description thereof is unnecessary.

As shown, piston 38 has an adjusting screw 40 threaded therein andengaged by one arm of a bell crank lever 30 which is pivoted upon astationary pin 91 and has a sleeve 92 threaded upon its other arm andlocked in an adjusted position by a lock nut 93. Sleeve 92 has acoupling 94 journaled thereon and pivotally connected to the push rod 82of pilot pump 70. The arrangement is such that the ratio between themovement of slide block 75 and the movement of piston 325 may be variedby loosening lock 3 and turning sleeve 92.

Adjusting screw 40 may be turned until spring 37 offers just enoughresistance to hold the bottom of notch 35 even with the bottom of port27 when pump 7 is creating just enough pressure to enable motor 5 toexert just enough torque to maintain the correct tension on strip 2 whenthe material first starts to accumulate on shaft 1.

Then as roll of material 3 increases in diameter and causes slide block75 to gradually move toward the right as previously explained, push rod82 will swing lever upon pin 91 and lever 90 will gradually compressspring 37 to thereby cause pump 7 to create a gradually increasingpressure with the resultant gradual increase in the torque exerted bymotor 5.

The invention herein set forth is susceptible of other modifications andadaptations without departing from the scope of the invention which ishereby claimed as follows:

1. In a hydraulic drive for rotating a winding shaft to which flexiblematerial is delivered by a machine and on which said material is woundinto a roll whereby the rotary speed of said shaft decreases relativelyto the linear speed of said material as said roll of material increasesin diameter, the combination of a hydraulic motor connected to saidshaft to rotate the same, a main pump connected to said motor forsupplying motive liquid thereto to enable said motor to drive saidshaft, and means for controlling the rate and pressure at which saidliquid is delivered to said motor including a control valve casinghaving a bore and an outlet port and a counterbore communicating withsaid bore, a pressure channel connecting said bore to the outlet of saidmain pump, a valve element fitted in said bore to control communicationbetween said pressure channel and said port and having its end subjectedto the pressure created by said pump, a piston fitted in saidcounterbore and forming therewith a pressure chamber, means fortransmitting force from said piston to said valve element, an auxiliarypump connected to said pressure chamber, a resistance valve connected tosaid auxiliary pump to permit it to discharge liquid therethrough andhaving a spring to resist said discharge of liquid and thereby enablesaid auxiliary pump to create in said chamber a pressure which causessaid piston to urge said valve element toward its closed position with aforce proportional to the resistance of said spring, and meansresponsive to the speed of said shaft decreasing for increasing theresistance of said resistance valve spring.

2. A hydraulic drive according to claim 1 in which said speed responsivemeans includes a first pilot pump driven at a speed proportional to thelinear speed of said material, a second pilot pump driven at a speedproportional to the rotary speed of said shaft so that the speed of saidsecond pilot pump decreases as the roll of material on said shaftincreases in diameter, said second pilot pump having a displacementvarying member continuously urged toward a minimum displacement positionand a servomotor for moving said member toward a maximum displacementposition, a first fluid channel connecting the outlet of said secondpilot pump to the inlet of said first pilot pump, a second fluid channelconnecting the outlet of said first pilot pump to the inlet of saidsecond pilot pump, a third fluid channel connecting said second channelto said servomotor to permit liquid to flow to said servomotor andenable it to move said displacement varying member toward its maximumdisplacement position in response to the speed of said second pilot pumpdecreasing relatively to the speed of said first pilot pump, and aconnection between said member and said resistance valve spring toenable said member during movement thereof to increase the resistance ofsaid spring.

3. A hydraulic drive according to claim 2 in which said connectionincludes a lever having one end thereof pivotally held in a stationaryposition, thrust transmitting means movable with said displacementVarying member and having a pivotal connection with said lever at apoint intermediate the ends thereof, a compressor engaging saidresistance valve spring and having a pivotal connection with said leverat a point spaced from said first mentioned point, and means for varyingthe distance between said pivotal connections.

4. In a hydraulic drive for rotating a Winding shaft to which flexiblematerial is delivered by a machine and on which said material is woundinto a roll whereby the rotary speed of said shaft decreases relativelyto the linear speed of said material as said roll of material increasesin diameter, the combination of a hydraulic motor connected to saidshaft to rotate the same, a main pump connected to said motor forsupplying motive liquid thereto to enable said motor to drive saidshaft, and means for controlling the rate and pressure at which saidliquid is delivered to said motor including a control valve casinghaving a bore and an outlet port and a counterbore communicating withsaid bore, a pressure channel connecting said bore to the outlet of saidmain pump, a valve member having one part thereof fitted in said bore tocontrol communication between said channel and said port and anotherpart thereof arranged in said counterbore, said valve member being urgedtoward open position by the pressure in said channel, a piston fitted insaid counterbore and forming therewith a pressure chamber, a springarranged between said valve member and said piston for urging said valvemember toward closed position with a force proportional to theresistance of said spring, an auxiliary pump connected to said pressurechamber, a resistance valve connected to said auxiliary pump to permitit to discharge liquid therethrough and having a spring to resist saiddischarge of liquid and thereby enable said auxiliary pump to create insaid chamber a pressure which enables said piston to maintain theresistance of said first mentioned spring proportional to the resistanceof said resistance valve spring, and means responsive to the speed ofsaid shaft decreasing for increasing the resistance of said resistancevalve spring.

5. A hydraulic drive according to claim 4 in which said speed responsivemeans includes a first pilot pump driven at a speed proportional to thelinear speed of said material, a second pilot pump driven at a speedproportional to the rotary speed of said shaft so that the speed of saidsecond pilot pump decreases as the roll of material on said shaftincreases in diameter,

said second pilot pump having a displacement varying member continuouslyurged toward a minimum displacement position and a servo-motor formoving said member toward a maximum displacement position, a

first fluid channel connecting the outlet of said second pilot pump tothe inlet of said first pilot pump, a second fluid channel connectingthe outlet of said first pilot pump to the inlet of said second pilotpump, a third fluid channel connecting said second channel to saidservo-motor to permit liquid to flow to said servo-motor and enable itto move said displacement varying member toward its maximum displacementposition in response 10 to the speed of said second pilot pumpdecreasing relatively to the speed of said first pilot pump, and aconnection between said member and said resistance valve spring toenable said member during movement thereof to increase the resistance ofsaid spring.

6. A hydraulic drive according to claim 5 in which said connectionincludes a lever having one end thereof pivotally held in a stationaryposition, thrust transmitting means movable with said displacementvarying member and having a pivotal connection with said lever at apoint intermediate the ends thereof, a compressor engaging saidresistance valve spring and having a pivotal con nection with said leverat a point spaced from said first mentioned point, and means for varyingthe distance be- 7 tween said pivotal connections.

7. In a hydraulic drive for rotating a winding shaft to which flexiblematerial is delivered by a machine and on which said material is woundinto a roll whereby the rotary speed of said shaft decreases relativelyto the linear speed of said material as said roll of material increasesin diameter, the combination of a hydraulic motor connected to saidshaft to rotate the same, a variable displacement main pump connected tosaid motor for supplying motive liquid thereto to enable said motor todrive said shaft, said pump having a displacement varying elementcontinuously urged toward a maximum displacement position and aservo-motor for moving said element toward a minimum displacementposition, and means for controlling the rate and pressure at which saidliquid is delivered to said motor including a control valve casinghaving a bore and an outlet port and a counterbore communicating withsaid bore, a pressure channel connecting said bore to the outlet of saidmain pump, a channel connecting said port to said servo-motor, a valvemember having one part thereof fitted in said bore to controlcommunication between said channel and said port and another partthereof arranged in said counterbore, said valve member being urgedtoward open position by the pressure in said channel, a piston fitted insaid counterbore and forming therewith a pressure chamber, means fortransmitting force from said piston to said valve element, an auxiliarypump connected to said pressure chamber, a resistance valve connected tosaid auxiliary pump to permit it to discharge liquid therethrough andhaving a spring to resist said discharge of liquid and thereby enablesaid auxiliary pump to create in said chamber a pressure which causessaid piston to urge said valve ele ment toward its closed position witha force proportional to the resistance of said spring, said valve memberbeing adapted to open said port to said pressure channel and per mitliquid to flow from said main pump to said servo-motor and cause it tomove said displacement varying element in a direction to reduce thedisplacement'of said main pump in response to the force exerted uponsaid valve member by main pump pressure exceeding the force exertedthereon by the pressure in said chamber, and means responsive to thespeed of said shaft decreasing for increasing the resistance of saidresistance valve spring.

8. A hydraulic drive according to claim 7 in which said speed responsivemeans includes a first pilot pump driven at a speed proportional to thelinear speed of said material, a second pilot pump driven at a speedproportional to the rotary speed of said shaft so that the speed of saidsecond pilot pump decreases as the roll of material on said shaftincreases in diameter, said second pilot pump having a displacementvarying member continuously urged toward a minimum displacement positionand a servo-motor for moving said member toward a maximum displacementposition, a first fluid channel connecting the outlet of said secondpilot pump to the inlet of said first pilot pump, a second fluid channelconnecting the outlet of said first pilot pump to the inlet of saidsecond pilot pump, a third fluid channel connecting said second channelto said servo-motor to permit liquid to flow to said servo-motor andenable it to move said displacement 1 1 varying member toward itsmaximum displacement position in response to the speed of said secondpilot pump decreasing relatively to the speed of said first pilot pump,and a connection between said member and said resistance valve spring toenable said member during movement thereof to increase the resistance ofsaid sprin 9. A hydraulic drive according to claim 8 in which saidconnection includes a lever having one end thereof pivotally held in astationary position, thrust transmitting means movable with saiddisplacement varying member and having a pivotal connection with saidlever at a point intermediate the ends thereof, a compressor engagingsaid resistance valve spring and having a pivotal connection with saidlever at a point spaced from said first mentioned point, and means forvarying the distance between said pivotal connections.

it). In a hydraulic drive for rotating a winding shaft to which flexiblematerial is delivered by a machine and on which said material is woundinto a roll whereby the rotary speed of said shaft decreases relativelyto the linear speed of said material as said roll of material increasesin diameter, the combination of a hydraulic motor connected to saidshaft to rotate the same, a variable displacement main pump connected tosaid motor for supplying motive liquid thereto to enable said motor todrive said shaft, said pump having a displacement varying elementcontinuously urged toward a maximum displacement position and aservo-motor for moving said element toward a minimum displacementposition, and means for controlling the rate and pressure at which saidliquid is delivered to said motor including a control valve casinghaving a bore and an outlet port and a counterbore communicating withsaid bore, a pressure channel connecting said bore to the outlet of saidmain pump, a channel COnnecting said port to said servo-motor, a valvemember havin' one part thereof fitted in said bore to controlcommunication between said channel and said port and another partthereof arranged in said counterbore, said valve member being urgedtoward open position by the pressure in said channel, a piston fitted insaid counter bore and forming therewith a pressure chamber, a springarranged between said valve member and said piston for urging said valvemember toward closed position with a force proportional to theresistance of said spring, an auxiliary pump connected to said pressurechamber, a resistance valve connected to said auxiliary pump to permitit to discharge liquid therethrough and having a Spr nfl to resist saiddischarge of liquid and thereby enable said auxiliary pump to create insaid chamber a pressure which enables said piston to maintain theresistance of said first mentioned spring proportional to the resistanceof said resistance valve spring, said valve member being adapted to opensaid port to said pressure channel and permit liquid to flow from saidmain pump to said servomotor and cause it to move said displacementvarying element in a direction to reduce the displacement of said mainpump in response to the force exerted upon said valve member by mainpump pressure exceeding the force exerted thereon by the pressure insaid chamber, and means responsive to the speed of said shaft decreasingfor increasing the resistance of said resistance valve spring.

ll. A hydraulic drive according to claim 10 in which said speedresponsive means includes a first pilot pump driven at a speedproportional to the linear speed of sai material, a second pilot pumpdriven at a speed proportional to the rotary speed of said shaft so thatthe speed of said second pflot pump decreases as the roll of material onsaid shaft increases in diameter, said second pilot pump having adisplacement varying member continuously urged toward a minimumdisplacement position and servo-motor for moving said member toward amaximum displacement position, a first fluid channel conthe outlet ofsaid first pilot pump to the inlet of said second pilot pump, a thirdfiuid channel connecting said second channel to said servo-motor topermit liquid to flow to said servo-motor and enable it to move saiddisplacement varying member toward its maximum displacement position inresponse to the speed of said second pilot pump decreasing relatively tothe speed of said first pilot pump, and a connection between said memberand said resistance valve spring to enable said member during movementthereof to increase the resistance of said spring.

12. A hydraulic drive according to claim 11 in which said connectionincludes a lever having one end thereof pivotally held in a stationaryposition, thrust transmitting means movable with said displacementvarying member and having a pivotal connection with said lever at apoint intermediate the ends thereof, a compressor engaging saidresistance valve spring and having a pivotal connection with said leverat a point spaced from said first mentioned point, and means for varyingthe distance between said pivotal connections.

13. In a hydraulic drive for rotating a Winding shaft to which flexiblematerial is delivered by a machine and on which said material is woundinto a roll whereby the rotary speed of said shaft decreases relativelyto the linear speed of said material as said roll of material increasesin diameter, the combination of a hydraulic motor connected to saidshaft to rotate the same, a constant displacement main pump connected tosaid motor for supplying motive liquid thereto to enable said motor todrive said shaft, and means for controlling the rate and pressure atwhich said liquid is delivered to said motor including a vcontrol valvecasing having a bore and an outlet port and a counterbore communicatingwith said here, a pressure channel connecting said bore to the outlet ofsaid main pump, a channel connecting said port to exhaust, a valveelement fitted in said bore to control communication between saidpressure channel and said port and having its end subjected to thepressure created by said pump, a piston fitted in said counterbore andforming therewith a pressure chamber, means for transmitting force fromsaid piston to said valve element, an auxiliary pump connected to saidpressure chamber, a resistance valve connected to said auxiliary pump topermit it to discharge liquid therethrough and having a spring to resistsaid discharge of liquid and thereby enable said auxiliary pump tocreate in said chamber a pressure which causes said piston to urge saidvalve element toward its closed position with a force proportional tothe resistance of. said spring, said valve element being urged towardopen position by the pressure created by said main pump and adapted toopen said port to said pressure passage and permit a part of the liquiddischarged by said main pump to escape to exhaust in response to theopening force exerted on said element by main pump pressure exceedingthe closing force exerted on said element by the pressure in saidchamber, and means responsive to the speed of said shaft decreasing forincreasing the resistance of said resistance valve spring.

14. A hydraulic drive according to claim 13 in which said speedresponsive means includes a first pilot pump driven at a speedproportional to the linear speed of said material, a second pilot pumpdriven at a speed proportional to the rotary speed of said shaft so thatthe speed of said second pilot pump decreases as the roll of material onsaid shaft increases in diameter, said second pilot pump having adisplacement varying member continuously urged toward a minimumdisplacement position and a servo-motor for moving said member toward amaximum displacement position, a first fluid channel connecting theoutlet of said second pilot pump to the inlet of said first pilot pump,a second fluid channel connecting the outlet of said first pilot pump tothe inlet of said second pilot pump, a third fluid channel connectingsaid second channel to said servo-motor to permaze to which flexiblematerial is delivered by a machine and 4 on which said material is woundinto a roll whereby the rotary speed of said shaft decreases relativelyto the linear speed of said material as said roll of material increasesin diameter, the combination of a hydraulic motor connected to saidshaft to rotate the same, a constant displacement main pump connected tosaid motor for supplying motive liquid thereto to enable said motor todrive said shaft, and means for controlling the rate and pressure atwhich said liquid is delivered to said motor including a control valvecasing having a bore and an outlet port and a counterbore communicatingwith said bore, a pressure channel connecting said bore to the outlet ofsaid main pump, a channel connecting said port to exhaust, a valvemember having one part thereof fitted in said bore to controlcommunication between said channel and said port and another partthereof arranged in said counterbore, said valve member being urgedtoward open position by the perssure in said channel, a piston fitted insaid counterbore and forming therewith a pressure chamber, a springarranged between said valve member and said piston for urging said valvemember toward closed position with a force proportional to theresistance of said spring, an auxiliary pump connected to said pressurechamber, a resistance valve connected to said auxiliary pump to permitit to discharge liquid therethrough and having a spring to resist saiddischarge of liquid and thereby enable said auxiliary pump to create insaid chamber a. pressure which enables said piston to maintain theresistance of said first mentioned spring proportional to the resistanceof said resistance valve spring, said valve member being urged towardopen position by the pressure created by said main pump and adapted toopen said port to said pressure passage and permit a part of the liquiddischarged by said main pump to escape to exhaust in response to theopening force exerted on said element by main pump pressure exceedingthe closing force exerted on said element by the pressure in saidchamber, and means responsive to the speed of said shaft decreasing forincreasing the resistance of said resistance valve spring.

'16. A hydraulic drive according to claim '15 in which said speedresponsive means includes a tfirst pilot pump driven at a speedproportional to the linear speed of said material, a second pilot pumpdriven at a speed proportional to the rotary speed of said shaft so thatthe speed of said second pilot pump decreases as the roll of material'onsaid shaft increases in diameter, said second pilot pump having adisplacement varying member continuously urged toward a minimumdisplacement position and a servo-motor for moving said member toward amaximum displacement position, a first fluid channel connecting theoutlet of said second pilot pump to the in- :let of said first pilotpump, a second fluid channel connecting the outlet of said first pilotpump to the inlet of said second pilot pump, a third fluid channelconnecti-ng said second channel to said servo-motor to permit liquid toflow to said servo-motor and enable it to move said displacement varyingmember toward its maximum displacement position in response to the speedof said second pilot pump decreasing relatively to the speed of saidfirst pilot pump, and a connection between said member and saidresistance valve spring to enable said member during movement thereof toincrease the resistance of said spring. I

17. In a hydraulic drive for rotating a winding shaft 14 to whichflexible material is delivered by a machine and on which said materialis wound into a roll whereby the rotary speed of said shaft decreasesrelatively to the linear speed of said material as said roll of materialincreases in diameter, the combination of a hydraulic motor connected tosaid shaft to rotate the same, a main pump connected to said motor forsupplying motive liquid thereto to enable said motor to drive saidshaft, and means for controlling the rate and pressure at which saidliquid is delivered to said motor including a control valve casinghaving a bore and an outlet port and a counterbore communicating withsaid bore, a pressure channel connecting said bore to the outlet of saidmain pump, a :valve element Lfitted in said bore to controlcommunication between said pressure channel and said port and having itsend subjected to the pressure created by said pump, .a piston fitted insaid counterbore, a spring engaging said piston and urging said valveelement toward closed position, a first pilot pump driven at a speedproportional to the linear speed of said material, a second pilot pumpdriven at a speed proportional to the rotary speed of said shaft so thatthe speed of said second pilot pump decreases as the roll of material onsaid shaft increases in diameter, said second pilot pump having adisplacement varying member continuously urged toward a minimumdisplacement position and a servo-motor for moving said member toward amaximum displacement position, a first fluid channel connecting theoutlet of said second pilot pump to the inlet of said first pilot pump,a second fluid channel connecting the outlet of said first pilot pump tothe inlet of said second pilot pump, a third fluid channel connectingsaid second channel to said servo-motor to permit liquid to flow to saidservo-motor and enable it to move said displacement varying membertoward its maximum displacement position in response to the speed ofsaid second pilot pump decreasing relatively to the speed of said firstpilot pump, and means responsive to movement of said displacementvarying member toward its maximum displacement position for causing saidpiston to increase the resistance of said spring.

18. A hydraulic drive according to claim 17 in which said last mentionedmeans is a mechanical linkage for transmitting motion from said memberto said piston and having an adjustment for varying the ratio betweenthe movement of said member and the resultant movement of said piston.

19. In a hydraulic drive for rotating a winding shaft to which flexiblematerial is delivered by a machine and on which said material is woundinto a roll whereby the rotary speed of said shaft decreases relativelyto the linear speed of said material as said roll of material increasesin diameter, the combination of a hydraulic motor connected to saidshaft to rotate the same, a variable displacement main pump connected tosaid motor for supplying motive liquid thereto to enable said motor todrive said shaft, said pump having a displacement varying elementcontinuously urged toward a maximum displacement position and hydraulicmeans for moving said element toward a minimum displacement position,and means for controlling the rate and pressure at which said liquid isdelivered to said motor including a control valve casing having a boreand an outlet port and a counterbore communicating with said bore, fluidchannels connecting said port and said counterbore to said hydraulicmeans, a pressure channel connecting the end of said bore to the outletof said main pump, a valve element fitted in said bore and in saidcounterbore to control the flow of liquid to and from said hydraulicmeans and having its end subjected to the pressure created by said pump,a piston fitted in said counterbore, a spring engaging said piston andurging said valve element toward closed position, a first pilot pumpdriven at a speed proportional to the linear speed of said material, asecond pilot pump driven at a speed proportional to the rotary speed ofsaid shaft so that the speed of said second pilot pump decreases as the15 roll of material on said shaft increases in diameter, said secondpilot pump having a displacement varying member continuously urgedtoward a minimum displacement position and a servo-motor for moving saidmember toward a maximum displacement position, a first fluid channelconnecting the outlet of said second pilot pump to the inlet of saidfirst pilot pump, a second fluid channel connecting the outlet of saidfirst pilot pump to the inlet of said second pilot pump, a third fiuidchannel connecting said second channel to said servo-motor to permitliquid to flow to said servo-motor and enable it to move saiddisplacement varying member toward its maximum displacement position inresponse to the speed of said second pilot pump decreasing relatively tothe speed of said first pilot pump, and means responsive to movement ofsaid 15 2,573,938

1 5 displacement varying member toward its maximum displacement positionfor causing said piston to increase the resistance of said spring.

20. A hydraulic drive according to claim 19 in which said last mentionedmeans is a mechanical linkage for transmitting motion from said memberto said piston and having an adjustment for varying the ratio betweenthe movement of said member and the resultant movement of said piston.

References Cited in the file of this patent UNITED STATES PATENTS TylerJuly 4, 1939 Tyler et al. Nov. 6, 1951

